These BCTs sound awfully complicated and standardised at a very low level. I do agree that the AFFS needs a strong structure though. So how about this as an alternate view:
The history of the AFFS is one of trials and tribulations. For much of their history they have suffered poor co-ordination and a lack of professionalism, plagued by regional rivalries even after the Davion Civil War of the 26th century and hamstrung by the 'cult of the mechwarrior' well into the 30th century. The first armed forces of the Federated Suns, the Federated Peacekeeping Forces, were able to cope against the individual Capellan states but against the united Capellan Confederation or the Draconis March they were less effectual. Replaced by First Prince Simon Davion with the Armed Forces of the Federated Suns, the new AFFS was a collection of five armies, each answering to a different Prince and suffering accordingly. Only under Alexander Davion would it become a single unified force and even then it was underfunded and eventually decimated by transfers to the Star League.
The next major advance of the AFFS came after the War of Davion Succession in the early 28th century. Richard Davion and his nephew John Davion committed to strengthen the AFFS following the humiliation of its poor performance against the DCMS. SLDF soldiers retiring into the Federated Suns were actively recruited as consultants and the entire AFFS was reorganised on the pattern of the SLDF's regiments, divisions and regimental combat teams - notwithstanding that the much smaller AFFS might have benefited by a more flexible organisation. This was also the first time the the Federated Suns Army gained its own aerospace assets, which until then had been the sole preserve of the Federated Suns Navy. By the Amaris Crisis, the AFFS felt it was ready for another war.
The First Succession War proved the AFFS calamitiously wrong: the logistics of moving such cumbersome forces were beyond them and only the ability to raise massive numbers of reinforcements from the system of militia and reserves set up by Richard Davion prevented the collapse of the AFFS as DCMS forces fought their way almost to New Avalon itself. However with the presence of SLDF and SLDF-trained soldiers in the Crucis Lancers and the Deneb Light Cavalry, the pattern of large multi-regimental Divisions remained, although in practise these would be scattered across several worlds operating in effectively independent battle groups.
The experience of the First Succession War led to several improvements during the Second where the AFFS proved able to hold its own, particularly on the Capellan front, re-organising strategically to create the March Militias and the PDZ of the border marches. However these benefits were not applied systematically until the reign of Melissa Davion in the late 29th century and the reforms that created the modern AFFS.
Melissa's reforms acknowledged the fact that maintaining three regiment brigades of BattleMechs was not compatible with guarding the long borders of the AFFS. Instead, each division was reorganised around a single BattleMech regiment, from which it took its name and an armoured brigade was permanently assigned, supplementing the two infantry brigades, aerospace wing, aviation wings, artillery and other supporting arms. In addition, the informal Anglo-French rank titles used before Richard Davion's reforms were restored. Thus, the organisation became:
1. The 'block': a single vehicle or an infantry squad of 7 men and their transport. Squads and vehicle crews are led by a Sergent, usually with a Caporal to support him (more junior soldiers hold the rank of Soldat). Mechwarriors and Aerospace pilots who have risen through the ranks hold this rank, while Academy graduates have the title of Subaltern (and rank slightly junior to Sergents) until they have six months of active service (usually in an Academy Cadre) when they are promoted to Sous-Lieutenant, which outranks Sergent.
2. The lance or platoon, led by the Lieutenant, is made up of four squads or vehicles (except jump infantry platoons which only use three squads or aerospace lances which contain two fighters). While the AFFS is perfectly happy to group dissimilar tanks and mechs into lances, as long as there is a sound tactical justification and the logistical demands are bearable, usually they are at least similarly mobile - all Mechs can or cannot jump, all vehicles are tracked or are all hovercraft, etc. (Artillery lances usually contain three artillery pieces and a recon vehicle or squad to act as spotter(s).) Lieutenants are expected to maintain the cohesion of their force and utilise tight co-ordination.
3. The company, led by a Captaine, and made up of three lances or platoons. This is the standard mission force and its quite common for companies to operate on their own for raids or detached operations. While companies are not usually combined arms, they do usually include lances of complementary capability and it is quite common for additional platoons to be attached for mission purposes, creating combined arms Combat Teams.
4. The battalion, led by a Chef de Battalion, contains three or four companies and often a command platoon or lance (generally larger battalion sizes are found in the Capellan March and smaller ones in the Draconis March). Battalions almost always operate independently from their parent regiment and quite commonly exchange a company with a battalion from another regiment. These semi-permanent combined arms Task Forces are the largest units where the commanding officer is likely to be directly fighting and not operating from a command centre and the Chef de Battalion is therefore considered the height of the fighting soldier's aspirations with all others being mere staff officers. Several First Princes have been killed or seriously injured fighting at the head of Task Forces, to the detriment of the Federated Suns.
5. The regiment, led by a Lieutenant Colonel, is an administrative unit responsible for the logistical demands of supplies, personnel and training for the troops in the battalions. An officer who seeks high command must serve as a Lieutenant Colonel to get this experience. Most regiments include three or four battalions, but it is rare to see more than one at the regimental depot at a time. Regiments are critical to a soldier's identity however: transfers between regiments are rare and a Lieutenant Colonel probably knows every officer and most NCOs personally. This can be important as the Lieutenant Colonel has the 'final word' all recommendations to award a medal to a soldier in his regiment (political pressure can be applied at times).
6. The Combat Command, led by a Colonel, contains up to nine battalions or Task Forces. This is the highest tactical unit of the AFFS and usually contains units from all arms along with permanently assigned support elements. Sometimes these units are referred to as Regimental Combat Teams, usually when they are not assigned to a Division. Academy Cadres are usually in the latter catagory as are regiments 'loaned' to the AFFS by powerful nobles (e.g. the Capellan Dragoons).
7. The Brigade, containing several regiments, is of relatively minor importance to the AFFS and the term has come to mean all regiments of a given type within a brigade. They are each headed by a General de Brigade and these officers act as senior staff officers within a brigade, assigned responsibility at the whim (or preferably careful deliberation) of their commander. A General de Brigade not entrusted with any duties beyond notional command of the regiments is being seriously snubbed and unlikely to advance further.
8. The Division is the main strategic unit of the AFFS, containing a BattleMech regiment, a brigade of two or three armoured regiments, a brigade of five or six infantry regiments, at least two aerospace battalions and usually an artillery battalion. The General de Division will then divide his forces into three or four Combat Commands, although usually these are a matter of tradition and only altered as needed. All PDZ have a permanently assigned Division of the March Militia
9. The Corps is a regional designation: all Divisions and independent regiments or RCTs in a PDZ or CR are part of the region's Corps and answerable to its General de Corps. The Corps is primarily a staff responsible directing the defense of the region and with the administration of military matters.
10. The Armee, led by a Marshal, is made up of all armed forces in an operational area or all armed forces assigned to a major campaign. Marshals also head major departments in the administration of the AFFS and are subject only to the First Prince, his or her Champion, or to the Marshal d'Armee should one be appointed.